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Cypriano G da Trindade Neto Ana LP Fernandes Ana IB Santos Waldenice A Morais Marcos VM Navarro Tereza NC Dantas Mrcia R Pereira Jos LC Fonseca 《Polymer International》2005,54(4):659-666
Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry 相似文献
3.
Gonzalo Martínez‐Barrera Enrique Vigueras‐Santiago Susana Hernndez‐Lpez Gonzalo Martínez‐Barrera Witold Brostow Carmina Menchaca‐Campos 《Polymer Engineering and Science》2005,45(10):1426-1431
Fiber reinforced concrete (FRC) contains fibers physically mixed with gravel, sand, cement, and water. So far, adequate mechanical performance of FRC has been obtained at high cost and using complex technologies; important here is the geometry and surface characteristics of the polymers. We have modified polymeric‐fiber surfaces by using gamma radiation. Irradiated polypropylene (PP) fibers were submitted to 0, 5, 10, 50, and 100 kGy of gamma irradiation dosages. First, tensile strength of PP fibers was evaluated, and then fibers blended at 0, 1.0, 1.5, and 2.0% in volume with Portland cement, gravel, sand, and water. The highest values of compressive strength were obtained with irradiated‐fibers at 10 kGy and 1.5% in volume of fiber. The result is 101 MPa, as compared to 35 MPa for simple concrete without fibers. POLYM. ENG. SCI., 45:1426–1431, 2005. © 2005 Society of Plastics Engineers 相似文献
4.
Joaquín Cortés Eliana Valencia Gonzalo Aguila Esteban Orellana Paulo Araya 《Catalysis Letters》2008,126(1-2):63-71
An experimental study is made of the time decay of activity of the CO–NO reaction on a Pd/Al2O3 looking at the effect on reaction order and apparent activation energy. The optimum kinetics parameters fitting the steady state data at moderate pressures are determined. The time decay curves are analyzed through various catalyst deactivation models. 相似文献
5.
J. L. Díez J. L. Navarro A. Sala 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2007,11(10):973-983
In this work, simple modifications on the cost index of particular local-model fuzzy clustering algorithms are proposed in
order to improve the readability of the resulting models. The final goal is simultaneously providing local linear models (reasonably
close to the plant’s Jacobian) and clustering in the input space so that desirable characteristics (regarding final model
accuracy, and convexity and smoothness of the cluster membership functions) are improved with respect to other proposals in
literature. Some examples illustrate the proposed approach. 相似文献
6.
C Faure M Besnard A Hirsch JF Mougenot M Peuchmaur JP Cezard J Navarro 《Canadian Metallurgical Quarterly》1996,23(4):419-421
N-(phosphonacetyl)-disodium L-aspartic acid (PALA) demonstrates a synergistic antitumor effect when combined with 5-Fluorouracil (5-FU) in in vitro studies. In a Phase II trial, 23 eligible patients with unresectable or metastatic adenocarcinoma of the stomach were treated with weekly i.v. bolus PALA (250 mg/M2) followed 24 hours later by a 24-hour infusion of 5-FU (2600 mg/M2) for an initial period of 8 weeks. No objective responses were noted. PALA and 5-FU is inactive against gastric adenocarcinoma at the doses and schedule used in this trial. 相似文献
7.
P Navarro J Sarasa D Sierra S Esteban J L Ovelleiro 《Water science and technology》2005,51(1):113-120
Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower. 相似文献
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M L Lema M del Pilar Navarro F J Mataix G Varela 《Archivos latinoamericanos de nutrición》1986,36(3):495-504
The effect of steam cooking (96 degrees C for 15 minutes) and drying at two temperatures, 70 degrees C and 110 degrees C, on nutritive value of mussel protein was studied. The measurements were carried out by nitrogen balance techniques in growing rats, and the nutritional parameters studied were: CD, BV and NPU. The crude digestibility (CD) values were: 87 +/- 1 and 82 +/- 1, and the biological values (BV), 80 +/- 1 and 74 +/- 1 for raw mussels, dried at 70 degrees C and at 110 degrees C respectively. This implies a significant decrease in the protein nutritive values of the mussel dried at a higher temperature. Cooking prior to drying significantly improved the digestibility and the biological value of the mussel's protein. In effect, improvement was so great, that the different drying temperatures did not affect the previously cooked product in a different way; therefore, the CD (94 +/- 1 and 94 +/- 1) and the BV (90 +/- 1 and 90 +/- 2) were the same for the mussel's protein, cooked and dried at 70 degrees C or at 110 degrees C. 相似文献
10.
Alexander Pavlov Gonzalo D Garcia De Fernando Juan A Ordoez Lorenzo Hoz 《Journal of the science of food and agriculture》1994,64(2):141-143
The β-hydroxyacyl-CoA-dehydrogenase (HADH) activity of unfrozen and thawed frog legs was investigated. The enzyme was extracted by either immersing frog legs in phosphate buffer 0.1 M, pH 6.0 at 25°C for 15 min or pressing them between trichinoscopy glasses. The enzyme activity was assayed using acetoacetyl-CoA as substrate and measured spectrophotometrically at 340 nm. It was possible by both extraction methods to distinguish between thawed and unfrozen samples although when the juice was obtained by pressing the HADH activity of the dilution was ~ 1.5 times higher than that obtained by immersion. The HADH activity was significantly higher (P≤0·001) in frozen-thawed frogs than in unfrozen legs because during freezing there is a release of HADH. No significative differences were found in the HADH activity in samples frozen in the temperature range -10 to -196°C. HADH activity was not affected by the storage time in crushed ice up to 6 days. 相似文献